The present invention relates to a nozzle used for supplying compressed air to clean machines or work pieces, and more particularly, to a nozzle designed for supplying adequate amounts of compressed air at acceptable noise levels.
Nozzles may be used for a variety of purposes including the cleaning of machines and work pieces. Nozzles may be operated automatically, or they may be hand-held by an operator who directs the exiting flow. Unfortunately, operator-held nozzles have a significant problem in that the level of noise emitted by the nozzle during operation can be unacceptably high when used for a significant period of time. Furthermore, when nozzles are used in an enclosed area, such as a factory, the reflective surfaces of the area can tend to increase the noise level.
A sound pressure level of 120 decibels has been determined by OSHA to be the threshold level of pain for a human being. In occupational situations, OSHA limits the exposure level of a person to noise levels of less than 90 dBA for an eight-hour period. Unfortunately, typical prior art nozzles used for particle blast cleaning apparatuses have been measured to emit noise levels as high as 130 decibels at an operator""s position.
Attempts within the industry have been made to reduce the noise level from air nozzles, such as that used on a safety air gun 200, shown in FIG. 1. The safety gun 200 includes a plug 202, which acts as a standoff from an operator. If any more than 30 psig of compressed air were to directly contact the skin of an operator, then the pressure could produce an air embolism within the operator. Thus, the plug 202 is a significant safety feature. The safety gun 200 further includes a plurality of small diameter holes 204 surrounding the plug 202. Airflow comes from the small diameter holes 204, which generate high-frequency noise, effectively lowering the noise level emitted by the gun 200. However, the safety gun 200 is limited by the number of holes 204 surrounding the plug 202. This limitation drastically reduces the output pressure and hence the performance and cleaning abilities of the gun 200.
Clearly, there is a need in the art for an air nozzle that can provide a significant amount noise reduction while not reducing the output pressure and hence the effectiveness of the nozzle.
According to one aspect, the present invention relates to a low-noise air delivery system including a nozzle plate having a plurality of tubes. Each tube acts as an independent nozzle with an external diameter (d). Also, each tube is spaced approximately two external diameters (2d) apart from an adjacent tube. The system further includes a hand-held portion coupled to the nozzle plate engageable to and in communication with an air supply.